Your reasoning and your answer were both correct. Discuss with the teacher. ("Discuss". DON'T fight.)
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Hello!</h2>
The answer is: 50% (0.5)
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Why?</h2>
Exponential growth equations are use to predict the growth (in function of time) using proportional information.
We can calculate the exponential growth using the following formula:

Where,
S, is the starting value
r, is the growth rate
t, is the time
So, we are given the function:

Where,
f(t), is the function,
3, is the starting value (lb)
0.5 (50%) is the growth rate
nt, is the time elapsed.
Hence,
From the given function, we know that the growth rate is equal to 0.5, and it's equal to 50%.
We can turn the growth rate given in real numbers to percent value by multiplying by 100

So, the growth rate is 50%.
Have a nice day!
100 center meters I think that should be right
She spent $9.
$16+$6 is $22, so the total $31 minus $22 leaves us with the $9 she spent for the taxi.
So, the answer is b multiplied by n or
b·n
Because she buys n books, and each book costs b dollars, so n·b gives you the total